System of control



R. E. HELLMUND.

SYSTEM OF CONTROL.

AFPHCATION FILED MAY 6, 1919.

1,367,473. Patented Feb. 1,1921.

2 SHEETS-SHEET I.

INVENTOR ToRNE WiTNESSES mM WM R. E. HELLMUND.

SYSTEM OF CONTROL.

ow M 1 cm Y A M D F- L H N 0 H A C u D: P A

Patented Feb. 1, 1921.

INV ENTOR frudo/fiHe/lmundi WITNESSES;

A ORNEY UNITED STATES PATENT OFFICE.

RUDOLF E. HELLMUND, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

SYSTEM OF CONTROL.

Original application filed June 19, 1915, Serial No.

Specification of Letters Patent.

Patented Feb. '1, 1921. 35,166. Divided and this application filed May 6,

1919. Serial No. 295,080.

To all whom it may concern:

Be it known that I, RUDOLF E. HELLMUND, a citizen of the German Empire, and a resident of Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification, this application being a division of application Serial No. 35,166, filed June 19, 1915, which has matured into Patent No. 1,303,307, granted May 13, 1919.

My invention relates to systems of control and it has special reference to the starting and acceleration of electric-railway vehicle motors and the like.

One object of my invention is to provide a system of the above-indicated character which shall be relatively simple and inexpensive in construction and efiicient and reliable in operation.

More specifically stated, it is one object of my invention to provide a system for effecting series-parallel acceleration of electric-motors by means of a motor-generator set of relatively small capacity, whereby the energy losses during acceleration are reduced to a minimum.

Heretofore, it has been common practice for systems of the type under consideration to embody a plurality of accelerating resistors, thus wasting a certain amount of energy whenever the motors were started. In another less prevalent type of system, the motors of auxiliary motor-generator sets have been connected in the main circuit as negative booster machines to permit of a gradual increase of the voltage applied to the propelling motors as the voltages of the motors of the sets were decreased. To return a portion of the accelerating energy to the supply circuit, a generator driven by the motor of the set has customarily been employed. The latter method is materially more efficient than the resistor type of acceleration, but has thedisadvantage of requiring machines of relatively large capacity, inasmuch as at the instant of starting, in

vide a system embodying a motor-generator set which is connected in circuit to effect efiicient acceleration of the main motors and which is, however, of relatively small necessary capacity, as hereinafter more fully set forth.

Other specific objects of my present invention will become evident from the following detailed description Itaken in conjunction with the accompanying drawing, wherein Figure 1 is a diagrammatic view of the main circuits of a system of control embodying my invention; Fig. 2 is a diagrammatic View of the auxiliary governing circuits for the system shown in Fig. 1; Fig. 3 is a sequence chart of well-known form for indicating the order of operation of the various controlling switches; and Fig. 4 to Fig. 7, inclusive, are simplified diagrammatic views illustrating various operating connections of my system.

Referring to Fig. 1, the system shown comprises supply-circuit conductors trolley and ground; a plurality of propelling elec tric motors, respectively having commutator-type armatures A1 and A2 and corresponding subdivided field windings F 1 and F2; a main-circuit reversing switch RS for simultaneously reversing the electrical relations of the corresponding armatures and field windings a motor-generator set having driving and generating armatures M and G, respectively, and shunt-connected field magnet windings MF and GF, the armature M being shown as provided with an additional series connected field magnet winding MFl; and a plurality of actuating switches, as indicated in the sequence chart of Fig. 3, for suitably controlling the operation of the main motors and of the motor generator set, in the manner to be described.

The driving armature M of the auxiliary motor-generator set is adapted to be connected in series-relation with the main machines during the major portion of the acceleration thereof, while the generating armature G is adapted to be connected in parallel relation to one or both of the main machines, as hereinafter more fully set forth. An exciting field winding MF for the driving armature .M is connected through a variable resistor R2 and a switch 122 across the supply circuit. An exciting field winding GF for the generating armature G i MC4 that is adapted to occupy a plurality of operative positions a. to u, inclusive.

Assuming that the reversing, switch RS and the master reverser MR occupy their respective forward positions and that the master controller MC4 is actuated to its ini tial position a, the operation of the system may be described as follows: a circuit is firstestablished from one terminal of the battery B, through conductor 124, control fingers 125 and 125, which are bridged by contact segment 126 of the master controller, conductor 127, contact-segment 128 of the master reverser, conductor 129, contact segment 130 of the reversing switch RS, conductor 131, the actuating coils of the switch LS, and conductors 132 and 133 to the opposite terminal of the battery B.

Other circuits are simultaneously established from the contact segment 126 through control fingers 134 to 140, inclusive, and conductors 141 to 147, inclusive, to the actuating coils of the switches 1, 3, 5, 7, 79, 80, 121, 122 and 123, respectively.

The motors are thus started into operation, with the armature M of the motorgenerator set for an instant carrying sul stantially the full supply-circuit voltage, while the armature G of the set operates at a relatively low voltage, by reason of the deenergization ofits field magnet winding GF. See Fig. 4.

In positions Z), 0, d and e of the master controller, the contact segment 126 engages control fingers 148, 149, 150 and 151, respectively, whereby the switches 46, 47, 7'7 and 78 are closed to effect the gradual strengthening of the field current traversii'ig the fielc magnet winding GF, by short-circuiting successive sections of the resistor R1, while in positions f, g, h and 2' of the controller,

the switches 79, 80, 121 and 122 are respectively opened by reason of the disengagement of the contact segment 126 from the corresponding control fingers, whereby the voltage of the armature M of the motor generator set is gradually reduced to substantially zero by increasing the active cireuit value of the resistor R2 and finally opening the circuit of the auxiliary field winding MF.

In position i of the controller, another circ it is established from contact segment 126. through control finger to the actuating coilof the switch 10, whereby the series connected field magnetwinding MFl of the motor-generator set is short-circuited. -11 hen the master controller is movedto its position j, the contact segment 126 engages control finger 153, whence circuit is completed through the actuating coil of the switch 9, thereby short-circuiting the armature M of the motor-generator set. Note Fig. 4. In this way, the residual magnetism of the auxiliary field winding is substantially nullified to eli'ect a practical demagnetization of the auxiliary armature M during the period of short-circuit'thereof before the transition of the main machines to parallel relation, as about to be described. Arcing and similar undesirable conditions are effectively prevented during the transition period.

In position it of the master controller. the switch 1 is opened by reason of the disengagement of contact segment 126 and the control finger 134, whereby the main niotors are connected in full-series relation across the supply circuit.

In position 1, the contact segment 126 again engages control fingers 137, 138, 135), and 1.41), whereby the switches 72), S0, 121. and 122 are closed to effect full excitation of the field winding Ml of the motor-generator set. \Vhen the master controller is moved to position at, the contact segment 126 engages control finger 154, whence circuit is completed through the actuating coil of the switch 2, whereby the voltage of the armature A2, which is thus connected in parallel relation with the armature (1r of the motor-generator set, is increased to a predetermined value somewhat above onehalf of the supply-circuit voltage. See 1 in position a of the master controller, switches 23 and 9 are opened by reason of the disengagement of the contact segment 126 from the corresponding control fingers, and the motor having the arn'iature A1 is thus temporarily excluded from circuit. However, in the succeeding position 0 of the controller, switch 1 is closed in the manner already described and switch 8 is closed by reason of the engagement of contact segment 126 with control finger 155. The previously disconnected motor is thus disposed in parallel-circuit relation with the motor, having the armature A2, which has beenincluded in circuit throughout. Note Fig. 6. It will be observed that, at this period of: the main motor acceleration, the motorgenerator set supplies the entire accelerating current for a short time, but, under the existing voltage conditions, approximately one-half this current will be supplied by the armature M and one-half by the armature G of the motor-generator set.

In positions p, (j, r and 8 of the master controller, the switches 79, 80, 121 and 122 are respectively opened, in a manner similar to that already described, to gradually reduce the -voltageof the armature M to zero.

In position t, the switch 9 is again closed, whereby the main motors are connected in mutual parallel-circuit relation to the armature G across the supply circuit, the armature M of the motorenerator set being again short-circuited. gee Fig. 7.

When the master controller is moved to its final operative position u, the contact segment 126 engages control finger 156, whence circuits are completed through the parallel-connected actuating coils of the switches 4 and 6, and, simultaneously, the switches 5 and 7 are opened by reason of the disengagement of the contact segment 126 from the corresponding control fingers, whereby predetermined portions of each of the main field windings F1 and F2 are excluded from the main circuits to effect a further step in the acceleration of the main motors, in accordance with a familiar practice.

It will be observed that, in the system just described, the maximum current traversing the armature G of the motor-generator set does not exceed approximately one-half of the total main motor current at any time, or, in other words, is never more than onehalf as much as the current that would be required if the main propelling motors were permanently connected in parallel relation.

It should be noted that, during the acceleration of the main motors, the auxiliary field winding GF is strengthened and the weakening of the auxiliary field winding MF is subsequently effected, which is the best way to prevent arcing or flashing in both of the auxiliary machines. Whenever the current traversing the auxiliary generating armature G is relatively large, the voltage thereof is relatively low, so that field-flux distortion is not of material importance. However, full field strength for the armature G is obtained before the voltage thereof exceeds substantially one-half of the supply circuit voltage, while substantially fifty per cent. of the current taken by the main machines traverses the armature G. Subsequently, the voltage in question increases, but, since the current decreases, there is again but little danger of flashing. Consequently, the illustrated and described order of operation of the auxiliary field-controlling switches constitutes an important feature of the present system.

I do not wish to be restricted to the specific circuit connections or arrangement of parts herein set forth, as various modifications thereof may be efiected without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

v1. In a system of control, the combination with a supply circuit, and plurality of electric motors, of an auxiliary motorgenerator set, means for initially connecting said motors in series relation across the generating armature of said set, means for variably exciting the field windings of said set to vary the voltages of the armatures thereof and the accelerating voltage impressed upon the motors, means for effecting transition of the motors to mutual parallel relation to said auxiliary generating armature, and means for again variably exciting the field windings of the motor-generator set to effect further acceleration of the motors.

2. The method of operating a plurality of electric motors in conjunction with an auxiliary motor-generator set which consists in initially connecting the motors in series relation across the generating armature of said set, varying the voltages of said machine to effect predetermined acceleration of said motors, subsequently connecting the motors in parallel relation across said auxiliar generating armature, and again varying the voltages of said machines to effect further acceleration of the motors.

3. The method of operating a plurality of electric motors in conjunction with an auxiliary motor-generator set which consists in initially connecting the motors in series relation across the armature of the first machine of said set, the second machine thereof being connected in series relation with the motors, increasing the voltage of said first machine and decreasing the voltage of said second machine to effect predetermined acceleration of the motors, short-circuiting said second machine-armature at a relatively low voltage, connecting the first motor in parallel relation with said first machine-armature when a predetermined voltage thereof obtains, connecting the other motor in parallel relation to the first motor, and again operating the motor-generator set to effect further motor acceleration.

4. In a system of control, the combination with a supply circuit and a main electric motor, of an auxiliary motor-generator set, means for connecting the armature of one of the machines of said set in parallel relation to said main motor, means for connecting the armature of the second machine in series relation with the main motor, means for connecting the field windings of said machines in parallel relation across the armatures thereof, means associated with said field windings for independently varying the voltages of the respective machines from zero to a predetermined maximum value, and vice versa, to effect gradual acceleration of the main motor, and means for excluding from circuit that machine armature having zero voltage last.

5. In a system of control, the combination with a supply circuit, and a plurality of main dynamo-electric machines, of an auxili- &

ary motor-generator set, means for initially connecting said main machines in series relation, means for subsequently connectingthe main machines in parallel relation across the armature of one of the machines of said set, means for connecting the armature of the other auxiliary machine in series relation with the main machines, and means for varying the voltages of the auxiliary armatures to vary the voltages of themain machines.

6. In a system of control, the combination with a supply circuit, and a main dynamoelectric machine, of a plurality of auxiliary dynamo-electric machine armature windings connected to said supply circuit in series relation, means for initially connecting the main machine across one of the auxiliary armature windings and for subsequently connecting the main machine across both auxiliary armature windings, and means for substantially demagnetizing the other auxiliary armature winding previous to said subsequent connection.

7. In a system of control, the combination with a supply circuit, and a main dynamoelectric machine, of an auxiliary motor-generator set connected to said supply circuit, means for initially connecting said main machine across the armature of one of the machines of said set, means for varying the voltage of the auxiliary machinesto impress an increasing voltage upon the main machine to a certain stage, temporary means for substantially nullifying the effect of one auxiliary armature, and means for subsequently connecting the main machine across both armatures of said set.

8. In a system of control, the combination with a supply circuit, and a main electric motor, of an auxiliary motor-generator set having its armatures connected to said supply circuit in series relation, means for ini tially connecting said motor across a certain armature of said set, means for varying the voltage of said certain armature from substantially zero to substantially supply-circuit voltage, means for substantially demagnetizing the other auxiliary armature, and means for then connecting the motor across both machines of said set.

9. The method of operating a main electric motor in conjunction with an auxiliary motor-generator set which consists in ini tially connecting said motor across one of the armatures of said set, temporarily substantially demagnetizing the other auxiliary armature, and subsequently connecting the motor across both of the auxiliary armatures under predetermined main motor voltage conditions.

10. The method of operating a main electric motor in conjunction with an auxiliary motor-generator set which consists in 1nitially connect ngsald motor across one of the armatures of said set, varying the volt age of the auxiliary machines to impress an increasing voltage upon the motor, SHbSt-Mb tially demagnetizing and short-circuiting the other auxiliary armature, and subsequently connecting the motor across both of the auxiliary armatures.

11. The method of operating a main electric motor in conjunction with an auxiliary motor-generator set having its armatures connected to a supply circuit in series relation which consists in initially connecting said motor across a certain armature of said set, varying the voltage of said certain armature from substantially zero to substantially supply-circuit voltage, substantially demagnetizing and then short-circuiting the other auxiliary armature, and then connecting the motor across both machines of said set.

12. In a system of control, the combination with a supply circuit and a main electric motor, of an auxiliary motor-generator set, means for connecting the armature of one oi the machines of said set in parallel relation to said main motor, means for connecting the armature of the second machine in series relation with the main motor, means for connecting certain field windings of said machines in parallel relation across the armatures thereof, said second machine being also provided with a series-related field winding, means associated with the first-named field windings for independently varying the voltages of the respective machines l rom substantially zero to a predetermined maximum value, and vice versa, to effect gradual acceleration of the main mot-or, means for short -circuiting said series-related field winding, and means for then excluding from circuit said second machine armature.

13. In a system of control, the combination with a supply circuit, and a plurality of electric motors, of an auxiliary motorgenerator set, the driving armature thereof having a series-related field winding and each auxiliary armature having a shunt field winding, means for initially connecting said motors in series relation across the generating armature of said set, means for variably exciting the shunt field windings of said set to vary the voltages of the armatures thereof and the accelerating voltage impressed upon the motors, means for shortcircuiting said series-related field winding and then the corresponding auxiliary armature to connect the motors in full series relation, means for effecting transition of the motors to mutual parallel relation to said auxiliary generating armature, and means for again variably exciting the shunt field windings of the motor-generator set to effect further acceleration of the motors.

1 4. 111 a system of control, the combinm tion with a plurality of main dynamo-electric machines, of an auxiliary motor-generatorset, means for initially connecting said main machines in series relation across a certain machine of said set, means for varying the excitation of said auxiliary machines to accelerate the main machines to full series relation, and means, including a switch for connecting a point intermediate the main machines to a point intermediate the auxiliary machines, for eifecting transition of the main machines to mutual parallel relation to said certain auxiliary machine.

15. The method of operating a plurality of dynamo-electric machines from series to parallel relation in conjunction with a plurality of auxiliary-machine armatures respectively connected in series relation with and in parallel relation to said main Inachines that includes as a transitional step the connection'of a point intermediate the main machines to a point intermediate the auxiliary machines.

In testimony whereof, I have hereunto subscribed my name this 24th day of April, 1919.

RUDOLF E. I-IELLMUND. 

